Per-operational autotransfusion suction device

ABSTRACT

A per-operational autotransfusion suction device has a suction cannular 1 with a tabular section nozzle 5, communicating with an inner passage 6, 9 in the cannula, the cannula passage being connected to a blood collecting recipient 41 in which a partial vacuum can be created by a vacuum source, the cannula passage communicating with an anticoagulant supply circuit having an anticoagulant feed control valve 15. The device has an independent vacuum circuit for sucking in only air and is connected to the vacuum source 40, to the blood collection recipient and to the valve. The valve has a vacuum chamber connected to a vacuum circuit 13, the vacuum chamber 49 having a deformable wall connected to a stopper which can close the anticoagulant feed circuit, the stopper being biased towards a closed position by a spring and capable of being biased towards an open position by deformation of the deformable wall when the pressure in the vacuum chamber is sufficiently low. The vacuum circuit communicates with an air vent 14 which can be shut off manually.

BACKGROUND OF THE INVENTION

This invention concerns a suction device for autotransfusion of bloodduring surgery.

Homologous blood transfusions, i.e. the transfusion of compatible bloodfrom other persons, involves some risk of the transfer of illnesses suchas hepatitis and AIDS. They can also cause immunodepression and reducethe patient's natural defences. Finally, some patients refuse to receivethe blood of other persons because of their religious beliefs.

For these reasons autologous transfusion or autotransfusion is widelyused, i.e. transfusion of the patient's own blood. Autotransfusion canbe delayed in the sense that blood is taken from the patient and storedfor subsequent transfusion into the same person. This is not alwayspossible, however; the transfusion may be required urgently, forexample. In this case autotransfusion during surgery can be used, inwhich blood lost by the patient during a surgical procedure is collectedand transfused into the patient.

The device conventionally used for autotransfusion during surgeryincludes a suction canula connected by a flexible tube to adepressurised blood storage vessel. The suction canula is also connectedto an anticoagulant storage vessel. During the surgical procedure bloodlost by bleeding in the operative field is aspirated by the canula,mixed with the anticoagulant in the canula and collected in the storagevessel from which it is transfused into the patient.

A basic technical problem encountered with autotransfusion duringsurgery is to mix the blood and the anticoagulant in proportions thatlie within the correct range. With anticoagulants such as CPD(citrate-phosphate-dextrose), for example, or heparin or a mixture ofheparin and CAD (citric acid-dextrose), where a typical anticoagulantsolution for 1 liter of blood serum comprises 60 ml of AB 16 plus 30 000units of heparin, the ratio of the volume of anticoagulant to the volumeof blood collected has to be around 1:7, the optimum ratio, and must notexceed 1:5 or fall below 1:10. If the ratio is too high the compositionof the blood is too severely changed for the blood to be transfusedwhile if it is too low there is insufficient anticoagulant in themixture to prevent the blood from coagulating. At a ratio of around 1:7the chemical, enzyme and blood corpuscle morphology composition of theblood are only slightly altered and the concentration of theanticoagulant is sufficient to prevent coagulation. With otheranticoagulants the range of permissible values for the ratio of thevolume of anticoagulant to the volume of blood can be different.

General information on autotransfusion can be found in the followingpublications:

--ADHOUTE, NAHABOO, LANCELLE, MORA, ROUVIER--Autotransfusion en pratiquechirurgicale. J. Chir. 1977, 114, 17-24,

--ADHOUTE, NAHABOO, LANCELLE, MORA, ROUVIER--Autotransfusion: XIIIthWorld Congress of the International Cardiovascular Society. 30 August 30September 20, Tokyo, Japan.

--ADHOUTE, NAHABOO, REYMONDON, ORSONI--Application de l'autotransfusionen chirurgie vasculaire reglee, Lyon Chir., 1978, 74, 50-62,

--ADHOUTE, NAHABOO, LANCELLE, MORA, ROUVIER, BLEYN,ORSONI--Autotransfusion in Surgical Practice, Cardio. Vasc. Res. CenterBull, 1979, 18, 40-15, Texas Medical Center, Houston, Tx. 77030--USA,

--ADHOUTE, HENIN--Economie du sang en chirurgie. J. Chirurgie, Paris,1980, 117, 713-722.

--AUTOTRANSFUSION: Proceedings of the First InternationalAutotransfusion Symposium: Apr. 24-25, 1980, Blood Bank Laboratories,University of Maryland School of Medicine, Md. U.S.A. Elsevier/NorthHolland, N.Y., Amsterdam, Oxford,

--ADHOUTE, AYOUB, REYMONDON, GAUTHIER--Autotransfusion peroperatoired'hemoperitoines en Chirurgie traumatique d'urgence: J. Chir., Paris,1988, 123, N 2, pp. 92-96, Masson, Paris, 1988,

--ADHOUTE--Autotransfusion: Utiliser son propre sang. Springer-VerlagFrance, 26 rue des Carmes, Paris, 1989.

--ADHOUTE--Autotransfusion: using your own blood. Springer-Verlag,Heidelberg, Federal German Republic, 1991.

A solution to the technical problem of controlling the concentration ofanticoagulant in the aspirated blood is proposed in French patentapplication No 2 503 566. This document describes a suction canula forautotransfusion during surgery with a suction nozzle at one end and theopposite end connected by a flexible tube to a blood storage vesseldepressurised by a vacuum source. A tube connected to an anticoagulantsolution storage vessel opens into the canula near the suction nozzle:thus if the suction nozzle aspirates air the pressure drop in the canulaat the anticoagulant entry is too small for anticoagulant to beaspirated; however, if the suction nozzle is immersed in blood in theoperative field the suction of this blood causes a greater pressure dropin the canula and anticoagulant is therefore aspirated into it. Thedimensions of the anticoagulant feed tube as compared to those of thesuction nozzle are such that the ratio of the anticoagulant to thevolume of aspirated blood is approximately 1:7. However, when the canulais not being used to aspirate blood it continues to aspirate air and maytherefore aspirate lightweight materials around the operative field (thegown of a person near the operative field, for example) which couldblock the suction nozzle: the pressure drop in the canula is thenincreased with the result that anticoagulant is aspirated but no blood.The same thing can happen during the suction of blood if any debrisobstructs the suction nozzle and the user does not notice right away. Ifdebris enters the suction nozzle of the canula the user may not be ableto remove it quickly, in which case the vacuum source will have to beswitched off to stop the flow of anticoagulant. In the meantime arelatively large quantity of anticoagulant may have been aspirated intothe blood storage vessel with the result that the blood in it may beunfit for use. Also, when the canula is not aspirating blood itcontinues to aspirate air which then enters the blood storage vesselbefore it is aspirated therefrom by the vacuum source. Dust ormicroorganisms in suspension in the air can then collect in the blood orin a filter of the storage vessel so that the latter is no longersterile. Furthermore, this constant flow of air in contact with theblood in the storage vessel is a source of haemolysis: the bloodtransfused into the patient is then lacking in red corpuscles.

U.S. Pat. No. 3,964,484 also describes a suction canula forautotransfusion during surgery which seeks to maintain a constantanticoagulant to aspirated blood volume ratio. This canula has a suctionnozzle at one end and the opposite end is connected by a flexible tubeto a blood storage vessel depressurised by a vacuum source. The canulaalso has an air vent and is connected to an anticoagulant feed passagewhich opens into the canula near the suction nozzle. The anticoagulantfeed passage includes a valve to shut off the passage if the canula isnot depressurised and to open it when the canula is depressurised. Tothis end the valve includes a flexible, elastic diaphragm communicatingon one side with the interior of the canula and having the other sidepressed elastically against a plate onto which the anticoagulant feedpassage opens. If the canula is aspirating air through the suctionnozzle and/or through the vent the pressure drop inside it is small andthe flexible diaphragm of the valve remains elastically pressed againstthe plate and shuts off the anticoagulant feed passage. When the usershuts off the air vent and immerses the suction nozzle in blood thelatter is aspirated and the resulting pressure drop in the canula causesthe flexible diaphragm to be lifted away from the plate to open theanticoagulant feed circuit.

This suction canula also has its drawbacks:

1. When blood is not being aspirated the canula aspirates aircontinuously and this air enters the blood storage vessel, causing theproblems mentioned above.

2. While blood is being aspirated the suction canula may be totally orpartly blocked, by various kinds of debris, for example; the user cannotdetect this immediately and there may therefore be a period in whichanticoagulant is aspirated but no blood, or less blood; this may makethe blood already aspirated unusable for the reasons explained above.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a suction device forautotransfusion during surgery which firstly guarantees that theanticoagulant is mixed with the blood with the ratio of the volume ofanticoagulant to the volume of blood within a given range of values andsecondly does not degrade the blood collected.

The present invention consists in a suction device for autotransfusionduring surgery comprising a suction canula having a tubular suctionnozzle communicating with an interior passage of said canula, saidpassage of the canula being connected to a blood collection storagevessel adapted to be depressurised by a vacuum source, said passage ofthe canula communicating with an anticoagulant feed circuitincorporating an anticoagulant feed control valve, characterized inthat:

--said device includes an independent vacuum circuit adapted to aspirateonly air and connected to the vacuum source, to the blood collectionstorage vessel and to the valve,

--the valve includes a vacuum chamber connected to said vacuum circuit,said vacuum chamber having a deformable wall connected to a closuremember of the anticoagulant circuit adapted to shut off theanticoagulant feed circuit and said closure member being urged towards aclosed position by elastic means and adapted to be urged towards an openposition by deformation of said deformable wall when there is asufficient pressure drop in the vacuum chamber, and

--the vacuum circuit communicates with an air vent adapted to be shutoff manually.

The invention further consists in a suction canula for autotransfusionduring surgery comprising a canula body forming a sleeve and having atubular suction nozzle communicating with an interior passage of saidcanula, said passage of the canula being connected to a blood collectionstorage vessel adapted to be depressurised by a vacuum source, saidpassage of the canula communicating with an anticoagulant feed passageincorporating an anticoagulant feed control valve, characterized inthat:

--said canula includes an independent vacuum passage adapted to aspirateonly air connectable to the vacuum source and connected to the valve,

--the valve includes a vacuum chamber connected to said vacuum passage,said vacuum chamber having a deformable wall connected to a closuremember of the anticoagulant passage adapted to shut off theanticoagulant feed passage and said closure member being urged towards aclosed position by elastic means and adapted to be urged towards an openposition by deformation of said deformable wall when there is asufficient pressure drop in the vacuum chamber, and

--the vacuum passage communicates with an air vent adapted to be shutoff manually.

At least part of the canula is advantageously transparent so that a usercan see the blood flowing in said canula.

In one advantageous embodiment of the invention the closure member ofthe anticoagulant passage is movable between its closed position and amaximally open position to define an anticoagulant flow cross-sectionwhich varies continuously between zero and a maximal value.

Said elastic means of the valve advantageously comprises a compressionspring in the vacuum chamber, and the valve includes means for adjustingthe compressive force of the spring.

In one embodiment of the invention said deformable wall of the vacuumchamber has a first side communicating with the vacuum chamber and asecond side communicating with the anticoagulant feed circuit. Theanticoagulant feed passage closure member is advantageously made from anelastomer material, and the deformable wall of the vacuum chamber isadvantageously a flexible wall formed integrally or in one piece withthe anticoagulant feed passage closure member.

In another embodiment of the invention:

--the closure member of the anticoagulant passage is fastened to aclosure member of the air vent,

--both closure members are movable between a rest position in which theanticoagulant passage closure member shuts off said anticoagulantpassage and the air vent closure member opens the air vent and a forcedactive position in which the anticoagulant feed passage closure memberopens said anticoagulant feed passage to the maximum and the air ventclosure member shuts off the air vent,

--both closure members are mechanically coupled to actuator means formoving the two closure members between their rest and forced activepositions.

Advantageously, said deformable wall of the vacuum chamber has a firstside communicating with the vacuum chamber and a second side open to theatmosphere and the canula further comprises a deformable wall of theanticoagulant circuit having a first side communicating with theanticoagulant circuit and a second side open to the atmosphere, saiddeformable wall of the anticoagulant circuit being also fastened to thetwo closure members, and said actuator means comprise a lever connectedto the two closure members by first articulation means disposed betweenthe two deformable walls and said lever is connected to the body of thecanula by second articulation means, said lever also having one endprojecting from the body of the canula. In this case, in one embodimentof the invention, the two closure members are connected by a rod havinga cross-section smaller than that of the closure members and said firstarticulation means of the lever comprise a fork engaged with said rod.

Advantageously:

--the body of the canula includes a sleeve having a front end and avalve assembly fixed to the front end of the sleeve, said valve assemblyincluding a base body, an intermediate ring and a valve body in astacked arrangement,

--the two closure members and the rod connecting them move axially in acylindrical recess extending through the intermediate ring,

--the intermediate ring includes a lateral window through which thecylindrical recess of said intermediate ring is open to the atmosphere,and

--the lever is moulded in one piece with said intermediate ring, saidlever passes through said lateral window and said second articulationmeans comprise two bridges of material between the lever and theintermediate ring.

In one embodiment of the invention, the anticoagulant feed passageclosure member is made from an elastomer material, the deformable wallof the anticoagulant circuit is a flexible wall in one piece with theanticoagulant feed passage closure member, the air vent closure memberis made from an elastomer material, the deformable wall of the vacuumchamber is a flexible wall in one piece with the air vent closuremember, the deformable wall of the anticoagulant circuit has an outerperipheral edge trapped between the base body and the intermediate ringand the deformable wall of the vacuum chamber has an outer peripheraledge trapped between the valve body and the intermediate ring.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

--FIG. 1 shows one embodiment of a canula of the device in accordancewith the invention in partial longitudinal cross-section on the lineI--I in FIG. 3,

--FIG. 2 shows the canula from FIG. 1 from above in partialcross-section on the line II--II in FIG. 1,

--FIG. 3 is a rear view of the canula from FIG. 1 as seen in thedirection of the arrow III in FIG. 1,

--FIG. 4 is a perspective view of one embodiment of static mixer thatcan be used in the canula from FIG. 1,

--FIG. 5 is a perspective view showing the canula from FIG. 1 in moredetail and in cross-section on the line V--V in FIG. 2,

--FIG. 6 is a diagram showing the connection of the canula from FIG. 1to a vacuum circuit, to a blood storage vessel and to an anticoagulantstorage vessel,

--FIG. 7 is a view similar to FIG. 2 showing an alternative embodimentof the canula from FIGS. 1 to 6,

--FIG. 8 is a view similar to FIG. 1 showing another embodiment of thecanula of the device in accordance with the invention,

--FIG. 9 shows part of the canula from FIG. 8 to a larger scale to showthe details of its valve,

--FIG. 10 shows the canula from FIGS. 8 and 9 in cross-section on theline X--X in FIG. 9,

--FIG. 10a is a view in cross-section on the line A--A in FIG. 10, and

--FIG. 11 is a detail view in partial cross-section showing the closuremember of the valve from FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, the suction device in accordance with the inventionincludes a suction canula 1. The canula 1 includes a sleeve 2 extendingbetween a front end 3 and a rear end 4. For reasons that become clearbelow, the sleeve 2 is advantageously made from a transparent material,normally a plastics material.

The front end 3 is extended by a suction nozzle 5 used to aspirate bloodlost during surgery and normally made from plastics material, in theform of a tubular conduit which curves downwardly in the normal positionin which the canula is used. The suction nozzle 5 can be in one piecewith the sleeve 2, for example moulded in one piece with it and thencurved to shape. The suction nozzle 5 can instead be a separate partwhich is inserted into the front end 3 of the sleeve 2: a seal is thenprovided between the sleeve 2 and the suction nozzle 5 by peripheralrings on the outside of the suction nozzle which snap into complementarygrooves on the sleeve 2, for example, or by O-rings between the twoparts, or by any other known means; this means that the surgeon canselect a suction nozzle 5 whose shape is suited to the type of surgicalprocedure to be undertaken. The nozzle 5 can be permanently fixed (e.g.glued) to the sleeve 2. The suction nozzle 5 is itself advantageouslymade from a transparent material.

Inside the sleeve 2 the suction nozzle communicates with a longitudinalsuction passage 6 which in turn communicates with an anticoagulant feedpassage 7 and a secondary passage 8. The suction passage 6 is extendedas far as the rear end 4 of the sleeve 2 by a mixing chamber 9. Thesuction passage 6 can be cylindrical with substantially the same insidediameter as the suction nozzle 5 or conical, converging towards thechamber 9, for reasons that emerge below, or any other shape.

The mixing chamber 9 can be a cylindrical longitudinal cavity open atthe rear end 4 of the sleeve and with a diameter greater than that ofthe suction passage 6. The mixing chamber 9 includes a static mixer 10which is helical in this specific example. Alternatively, as shown inFIG. 4, the static mixer 10 can be made up of plane surfaces dividedinto two sets separated by a plane containing the axis of thecylindrical chamber 9: a first set of parallel surfaces 10a at an anglea to the axis of the chamber 9 and a second set of parallel surfaces 10bnot parallel to the surfaces 10a, being at the same angle α to the axisof the chamber 9, for example. The static mixer 10 can be of any otherkind provided that it creates turbulence in the flow of blood andanticoagulant from the suction passage 6 in order to mix themhomogeneously. The mixer 10 can instead be a non-static mixer, forexample a helical screw rotated by the flow of blood.

Examples of static mixers are given in U.S. Pat. Nos. 3,964,484,3,955,573 and 4,002,170.

The rear end of the mixing chamber 9 is fitted with an end-piece 11which holds the static mixer 10 in the chamber 3 and also connects thechamber 9 to a flexible tube (not shown) for conveying aspirated bloodto a storage vessel. The end-piece 11 can be fixed to the sleeve 2 byany means, for example screwing, force-fitting, snap-fastening, etc. Theend-piece 11 can feasibly be dispensed with, in which case the staticmixer 10 can be held in the chamber 9 by friction, gluing, welding orany other means, and the flexible tube for the aspirated blood can beconnected directly to the chamber 9.

Referring to FIGS. 2 and 3, the sleeve 2 also includes two longitudinalpassages which open at its rear end 4: a vacuum passage 13 whose rearend is connected by a flexible tube (not shown) to a vacuum source, andan anticoagulant feed passage 12 whose rear end connects via a flexibletube (not shown) to an anticoagulant storage vessel. As shown in FIG. 1,the vacuum passage 13 communicates with an air vent 14 in the upper partof the sleeve 2 of the canula 1. Both passages 12 and 13 also extendtowards an anticoagulant feed control valve 15 described in detailbelow.

As shown in FIG. 5, the valve 15 is housed in a cylindrical protrusion16 of the sleeve 2 which projects above the sleeve 2 when the canula 1is in its position of use, said protrusion 16 being substantiallyperpendicular to the longitudinal axis of the sleeve 2 and centred onthe anticoagulant feed passage 7 already described. The passage 7 opensinto the suction passage 6 perpendicularly thereto. The passage 7extends a certain distance towards the protrusion 16 and then widens inthe upward direction to form a frustoconical valve seat 17. The valveseat 17 is extended upwards by a cylindrical bore 18 and then by a taper19 which opens into a cylindrical or other shape recess 20 to form ashoulder 20a. The recess 20 has its open side at the top of theprotrusion 16. The anticoagulant feed passage 12 is extended by asmaller cross-section portion 12a which opens into the frustoconicalvalve seat 17 substantially perpendicular to its axis. The cross-sectionof the portion 12a is such that when the valve seat 17 is not shut offand blood is aspirated into the passage 6 due to the depressurization,anticoagulant is aspirated through the portion 12a and the passage 7 ata rate such that it is mixed with the blood with a ratio of the volume(or flowrate) of the anticoagulant to the volume (or flowrate) of theblood in a predetermined range of values. With an anticoagulant such asheparin or CPD (citrate-phosphate-dextrose) the ratio of the volume (orflowrate) of the anticoagulant to the volume (or flowrate) of the bloodshould be between 1:10 and 1:5 and preferably around 1:7. With otheranticoagulants the range of permissible values can be different. Thevacuum passage 13 opens into the recess 20 and the auxiliary passage 8joins the taper 19 to the suction passage 6.

A ring 21 whose shape is complementary to that of the recess 20 is afluid-tight fit in said recess 20. The ring 21 is normally made from asynthetic material. The ring 21 has at its center a cylindrical bore 22whose upper part is screwthreaded and it also has a radial passage 32through it below the threaded portion and communicating with the vacuumpassage 13 when the ring 21 is fitted into the recess 20. If theexterior shape of the ring 21 is that of a body of revolution, itadvantageously has a lug 24 on the outside cooperating with acomplementary shaped recess of the protrusion 16 to locate the radialpassage 23 in corresponding relationship to the outlet from the vacuumpassage 13 into the recess 20. The ring 21 can be fixed into the recess20 by snapping a peripheral ring 25 on the outside of the ring 21 into acomplementary shape groove in the recess 20. The ring 25 can be replacedwith a peripheral O-ring engaged in a peripheral groove in the recess 20and a corresponding peripheral groove in the ring 21. The ring 21 canalso be fixed permanently, for example glued, into the recess 20. Aknurled head screw 26 is screwed into the screwthreaded part of thecentral bore 22 in the top part of the ring 21. Also, a bearing disc 27is slidably mounted in the central bore 22 and includes a central rod27a extending towards the valve seat 17. A coil spring 28 is disposedbetween the bearing disc 27 and the knurled head screw 26 to urge thebearing disc 27 towards the shoulder 20a.

A flexible elastic diaphragm 29 is disposed between the ring 21 and theshoulder 20a. This diaphragm can simply be gripped between the ring 21and the shoulder 20a or it can be glued to the ring 21. The diaphragm 29can be made from latex, for example. The ring 21, the screw 26 and thediaphragm 29 define a vacuum chamber 49 communicating only with thevacuum passage 13.

The valve 15 includes a valve stem 30 having a frustoconical partadapted to seat in a fluid-tight manner on the valve seat 17 to shut offthe portion 12a of the anticoagulant feed passage 12 and a cylindricalpart adapted to slide in the cylindrical bore 18 to guide said valvestem 30. The cylindrical bore 18 and the cylindrical part of the valvestem 30 can be dispensed with without departing from the scope of thepresent invention. The valve stem 30 also has a central bore 31 intowhich the rod 27a of the bearing disc 27 is forced, though the diaphragm29. The valve stem 30 is therefore fastened to the central part of thediaphragm 29 and the bearing disc 27.

FIG. 6 shows the connection of the suction canula 1 to the vacuum source40, to the blood storage vessel 41 and to the anticoagulant storagevessel 42. The vacuum source 40 can be just a valve connected to avacuum circuit connected to a vacuum pump or to some other suctionsystem and connected by a flexible tube 50 to a Tee connector 45 whichconnects it to the collected blood storage vessel 41 via a flexible tube43 and to the vacuum passage 13 of the canula 1 via a flexible tube 44connected to the rear end 4 of the sleeve 2.

The storage vessel 41 for collected blood can in the conventional wayhave a rigid outer casing containing a flexible sachet in which theblood is collected, the outer casing and the flexible sachet both beingconnected to the flexible tube 43. The pressure drop at the vacuumsource 40, as measured by a pressure gauge 40a, can be in the order of30 mm to 60 mm of mercury, preferably 30 mm to 40 mm of mercury, toprevent corpuscular trauma.

The blood collection storage vessel 41, to be more precise the flexiblesachet in which the blood is collected, is connected to the mixingchamber 9 of the canula 1 by a flexible tube 46. The storage vessel 41usually incorporates a filter to hold back any debris aspirated with theblood. The filter can have a mesh size of 150 μm to 170 μm, for example.The storage vessel 41 is designed in the known way to prevent bloodbeing aspirated out of it towards the vacuum source 40.

Examples of blood storage vessels that can be used in the device of thepresent invention are described in U.S. Pat. No. 3,866,608 (equivalentto French patent 2,248,424) and U.S. Pat. No. 3,680,560 (equivalent toBelgian patent 753,552).

The anticoagulant storage vessel 42 is connected by a flexible tube 47to the anticoagulant feed passage 12 of the canula 1. The anticoagulantcan be heparin, CPD (citrate-phosphate-dextrose), a mixture of heparinand CAD (citric acid-dextrose), etc.

The suction canula operates as follows: if the air vent 14 of the vacuumpassage 13 is open air is aspirated towards the vacuum source 40 throughthe vent 14, the passage 13 and the tube 44. There is therefore a verysmall pressure drop in the flexible tube 43 and in the storage vessel 41in which the blood is collected, and no suction through the tube 46, thechamber 9, the passage 6 and the suction nozzle 5. There is no or verylittle pressure drop in the part of the vacuum passage 13 between theair vent 14 and the valve 15. The pressure drop in the vacuum chamber 49is therefore too small for the diaphragm to be lifted off the bearingdisc 27 and the valve stem 30; the frustoconical valve stem 30 istherefore held seated in a fluid-tight manner on the valve seat 17 bythe spring 28 and the section 12a of the passage 12 remains shut off.

Thus, provided the air vent 14 is open, there is no suction via thesuction nozzle 5 of the canula 1, the canula is not fed withanticoagulant and no air enters the collected blood storage vessel 41.This prevents haemolysis and pollution of the blood in the storagevessel 41.

If the user blocks the air vent 14 with a finger when the suction nozzle5 of the canula is not immersed in a liquid, air is aspirated by thevacuum source 40 via the suction nozzle 5, the passage 6, the mixingchamber 9, the flexible tube 46, the blood collection storage vessel 41and the tube 43. This causes air to enter the blood collection storagevessel 41 but does not represent normal use of the suction canula: theuser normally blocks the vent 14 only after immersing the suction nozzle5 in the blood to be aspirated, i.e. air enters the blood collectionstorage vessel only under exceptional circumstances. The flow of airproduces only a small head loss: there is thus a small pressure drop atthe Tee connector 45 and therefore in the flexible tube 44, the vacuumpassage 13 of the canula 1 and in the vacuum chamber 49 of the valve.The force of the spring 28 is therefore sufficient to counteract thissmall pressure drop and the valve stem 30 continues to be pressedagainst the valve seat 17 and the anticoagulant feed passage 12 remainsshut off. Thus suction of air with no suction of blood does not lead tosuction of anticoagulant. There is therefore no risk of the bloodalready collected deteriorating due to the suction of massive amounts ofanticoagulant.

If the user blocks the vent 14 after immersing the suction nozzle 5 ofthe canula in the blood escaping during the surgical procedure thepressure drop caused by the vacuum source 40 aspirates blood into thecollection storage vessel 41.

The flow of blood in the canula 1 and the tube 46 causes a large headloss and the pressure drop in the tube 43, the connector 45, the tube44, the vacuum passage 13 and the vacuum chamber 49 is similar to thatdue to the vacuum source 40, which is sufficient to counteract the forceof the spring 28 of the valve 15. The elastic diaphragm 29 is thereforeraised with the bearing disc 27 and the valve stem 30 which is thereforelifted off the valve seat 17: the anticoagulant feed passage 12 is nolonger shut off and due to the pressure drop in the suction passage 6the anticoagulant can flow from the storage vessel 42 via the tube 47,the passage 12 and its smaller cross-section portion 12a and theanticoagulant feed passage 7 into the suction passage 6 where it beginsto mix with the aspirated blood. The mixture is homogenized in themixing chamber 9 by the static mixer 10. The diaphragm 29 prevents theanticoagulant from being aspirated into the vacuum circuit.

If air bubbles are aspirated with the blood the pressure drop in thevacuum chamber 49 is reduced: the spring 28 therefore tends to push thevalve stem 30 towards the valve seat 17, but without it coming intocontact with the seat 17: because the stem 30 and the seat 17 arefrustoconical the anticoagulant flow cross-section between the stem 30and the seat 17 is reduced and the flowrate of the anticoagulant intothe suction passage 6 is reduced. The aspirated blood flowrate is alsodiminished because of the aspirated air, and the ratio of the flowrateof anticoagulant to the flowrate of blood in the mixture ofanticoagulant and blood therefore remains in the range of acceptablevalues defined above. The user can turn the knurled head screw 26 toadjust the compression force of the spring 28 and so vary theanticoagulant flowrate.

If the suction nozzle 5 is blocked by aspirated debris or for any otherreason, suction of blood stops or continues at a reduced rate: as thecanula is transparent the user can easily see that this has happened.The flow of the blood can be seen because of the air bubbles or bone ortissue debris aspirated along with the blood and any major change in theconcentration of anticoagulant in the aspirated blood or the suction ofanticoagulant only changes the color of the aspirated liquid in thecanula. The user can therefore react quickly and stop suction in orderto clear or change the suction canula.

The knurled head screw 26 can be dispensed with without departing fromthe scope of the invention. Likewise the valve stem 30 and the valveseat 17 can be cylindrical rather than frustoconical, although this isnot preferred as in this case the flowrate of anticoagulant is notvaried according to the blood flowrate as when the valve stem isfrustoconical and the portion of the passage 12 is either shut off oropen. The diaphragm 29 can be replaced by a piston sliding in and sealedto the bore 22: the disc 27 can function as this piston if its upwardtravel is limited so that it cannot rise above the passage 23, as inthis case anticoagulant can be aspirated into the vacuum circuit. If thediaphragm is dispensed with the disc 27 can be in one piece with thevalve stem 30.

The passage 6 can have a conical shape that converges towards thechamber 9: the Venturi effect then increases the pressure drop in thepassage 6 at the anticoagulant feed passage 7, facilitating the suctionof anticoagulant.

When the user stops blocking the air vent 14 suction of blood ceases andthe pressure drop in the vacuum chamber 49 is eliminated, as a result ofwhich the spring 28 pushes the bearing disc 27, the diaphragm 19 and thevalve stem 30 towards the valve seat 17 until said stem 30 is pressedonto said seat 17 and shuts off the anticoagulant feed passage 12: theflow of anticoagulant therefore ceases. If anticoagulant has collectedbetween the diaphragm 29 and the shoulder 20a is collected in the taper19 and evacuated to the passage 6 via the auxiliary passage 8: for thisreason it does not impede the closing of the valve 15.

FIG. 7 shows an alternative embodiment of the canula in accordance withthe invention which has an additional passage 48 communicating with thevacuum passage 13 and connected to the blood collection storage vessel41. The tube 50 and the Tee connector 45 of FIG. 6 are dispensed with,the tube 44 connects the passage 13 direct to the vacuum source 40 andthe tube 43 connects the passage 48 to the blood collection storagevessel 41. The air vent 14 can be either on the passage 13 or on thepassage 48. The device operates in the same way as described above.

FIGS. 8 through 11 show another embodiment of the canula according tothe invention. The structure and operation of this canula are similar tothose of the canula from FIGS. 1 to 7 and therefore need not bedescribed again in detail here. Components similar or identical to thoseof FIGS. 1 through 7 carry the same reference numbers as in FIGS. 1through 7 increased by 100.

Referring to FIG. 8, the canula 101 includes a sleeve 102 made frompolystyrene, for example, extending longitudinally between a front end103 and a rear end 104. A vacuum passage 113, an anticoagulant passage112 and a mixing chamber 109 extend longitudinally through the sleeve102. At the rear end 104 of the sleeve 102 the vacuum passage 113 isadapted to be connected to a flexible tube (not shown) connected to avacuum source, the anticoagulant feed passage 112 is adapted to beconnected to a flexible tube (not shown) connected to an anticoagulantstorage vessel and the mixing chamber 109 is adapted to be connected toa flexible tube (not shown) connected to a storage vessel in which theblood is collected. The mixing chamber 109 contains a static mixer 110as described above which can also be made from polystyrene and which ismerely nested inside the chamber 109. The mixing chamber 109advantageously has a smaller inside diameter rear end 109a to hold themixer 110 in place. The canula 101 includes a valve assembly 151 fixedto the front end 103 of the sleeve 102 and described in more detailbelow. The valve assembly 151 has a front end 151a and a rear end 151b.It contains a valve 115 for controlling the supply of anticoagulant.

A blood suction tube or nozzle 105 and an anticoagulant feed tube 107parallel to it extend towards the front from the valve assembly 151. Thetwo tubes are interconnected at their front end by a suction end-piece152. The end-piece 152 can include an inlet orifice 153 and two orifices154, 155 respectively receiving the tubes 105 and 107. The end-piece 152and the two tubes 105 and 107 can be made from PVC, for example. Bothtubes 105 and 107 can be force fitted, glued or fixed in any other wayinto the end-piece 152.

As shown in FIG. 9 the valve assembly 151 includes three stacked parts:a base body 156 at the bottom, an intermediate ring 157 and a valve body158 at the top. These three parts are assembled together by any knownmeans, for example by screws 159 which pass through the valve body 158and the ring 157 into the base body 156. In the example shown the basebody 156 and the valve body 158 are moulded from polystyrene and theintermediate ring 157 is moulded from acetal resin.

A suction passage 106 passes longitudinally through the lower part ofthe base body 156. The suction passage 106 extends between a front end106a which communicates with the blood suction tube 105 and a rear end106b which communicates with the mixing chamber 109. The blood suctiontube 105 is force-fitted or glued into the front end 106a of the passage106. The rear end 106b of the passage 106 forms an end-piece 160 whichis nested in the mixing chamber 109. The end-piece 160 is fixed into themixing chamber 109 by any known means such as force-fitting or glueing,for example. The end-piece 160 also helps to retain the static mixer 110in the mixing chamber 109.

The base body 156 also has an upper surface 161 on which a cylindricalcup 162 is formed. A cylindrical recess 163 at the center of thecylindrical cup 162 is extended downwardly by a conical recess 164. Thecylindrical recess 163 has a wider upper part 163a for reasons to beexplained below.

The base body 156 also includes a passage 112a extending between a rearend 112b communicating with the anticoagulant feed passage 112 and asmaller cross-section front end 112c which opens into the conical recess164. The rear end 112b of the passage 112a forms an end-piece 165 whichis nested in the passage 112. The end-piece 165 can be force-fitted orglued into the passage 112.

The base body 156 further includes a passage 166 extending between afront end 166a into which the anticoagulant feed tube 107 opens and arear end 166b which opens into the lower part of the conical recess 164.The anticoagulant feed tube 107 can be fixed into the passage 166 by anyknown means such as force-fitting or glueing, for example. In theexample shown, for reasons explained below, the rear end 166b of thepassage 166 must open into the conical recess 164 at a position belowthe position of the front end 112c of the passage 112a.

The ring 157 has a lower surface 167 and an upper surface 168. Acylindrical recess 169 extends vertically through it between its uppersurface 168 and its lower surface 167. The lower surface 167 of the ring157 has a cylindrical projecting part 170 adapted to nest in the cup 162of the base body. The upper surface 168 of the ring 157 incorporates acylindrical cup 171 similar to the cup 162 of the base body.

As shown in FIGS. 10 and 10a, the ring 157 includes a lateral window 172through which passes a lever 173. The lever 173 extends between anoutside end 174 and a forked inside end 175, the utility of which isexplained below. The lever 173 is joined to the ring 157 by two bridges176 of material extending laterally to each side of the lever 173, andadvantageously made from acetal resin. When a user presses the outsideend 174 of the lever vertically downwards, as explained below, thematerial bridges 176 are deformed elastically in torsion and when theuser releases the lever the elasticity of the material bridges 176returns the lever 173 to its original position.

Referring to FIG. 9, the valve body 158 has an upper surface 177 and alower surface 178. The lower surface 178 incorporates a cylindricalprojection 179 adapted to nest in the cylindrical cup 171 of the ring157. The valve body 158 includes a cylindrical recess 180 aligned withthe cylindrical recess 169 of the ring 157 and extending some distancefrom the lower surface 178 of the valve body. The upper surface 177 ofthe valve body includes an air vent 114 communicating with thecylindrical recess 180 of the valve body via a frustoconical valve seat181. The valve body 158 includes a passage 113a extending between a rearend 113b communicating with the vacuum passage 113 and a front end 113copening into the cylindrical recess 180, said cylindrical recess 180thus forming a vacuum chamber 149. The rear end 113b of the passage 113aforms an end-piece 182 which enters the passage 113. The end-piece 182can be fixed into the passage 113 by any known means such asforce-fitting or glueing, for example.

A valve assembly 183 is disposed inside the cylindrical recesses 180 and169. Referring to FIG. 11, the valve assembly 183 is made up of twosealing members 184, 185 joined together by a connecting rod 186. Thetwo sealing members 184, 185 are moulded from an elastomer material andare advantageously identical. The sealing member 184 has a cylindricalpart 187a extending axially between a rear end 188a and a conical frontend 189a. The conical front end advantageously includes a peripheral lipseal 190a. The rear end 188a incorporates a cylindrical recess 191a. Atan intermediate position along the length of the cylindrical part 187athe sealing member incorporates an outer ring 192a extended outwards bya thin annular flange 193a. Because it is thin the flange 193a isflexible and it is advantageously formed with at least one annularcorrugation 194a for reasons explained below. The sealing member 185 isidentical to the sealing member 184 and its various component parts areidentified by the same reference numbers as the component parts of thesealing member 184 with the suffix "b" instead of the suffix "a". In theembodiment of FIGS. 1 through 7 the closure member and the flexiblediaphragm can be replaced with a sealing member similar to the sealingmember 184. The rod 186, which can be moulded from polystyrene, isnested in the recesses 191 of the two sealing members 184, 185 and isfixed to the sealing members by any known means such as force-fitting orglueing, for example.

As shown in FIG. 9, the outside edge 195a of the sealing member 184 isgripped all around its perimeter between the bottom of the cup 162 andthe cylindrical part 170 and the outside edge 195b of the thin wall ofthe upper sealing member 185 is gripped all around its perimeter betweenthe bottom of the cup 171 and the cylindrical part 179. The uppersealing member 185 therefore forms a seal between the vacuum chamber 149and the recess 168 in the ring 157. Likewise, the lower sealing member184 forms a seal between the recess 168 in the ring 157 and theanticoagulant feed circuit.

A frustoconical spring 128 is disposed in the vacuum chamber 149. Thespring 128 bears on the ring 192b of the upper sealing member 185 whichurges the valve assembly 183 downwards. Thus when in the rest position,as shown in FIG. 9, the lip seal 190 of the lower sealing member 184 ispressed against the surface of the frustoconical recess 164, at a pointabove the end 166b of the passage 166 and below the end 112c of thepassage 112a. The lower sealing member 184 in the rest positiontherefore shuts off the anticoagulant feed passage 112. In this restposition the two branches of the fork 175 of the lever 173 are disposedone on each side of the connecting rod 186 of the valve assembly 183 andthe branches of the fork 175 are a small distance below the rear end 188of the upper sealing member 185. The purpose of the wider upper portion163a of the cylindrical recess 163, already described, is simply toprevent interference between the ring 192a and the intermediate ring157.

If a user blocks the air vent 114 with his or her finger while thecanula is in use blood and anticoagulant are aspirated in the same wayas by the canula of FIGS. 1 to 7. There is sufficient clearance betweenthe fork 175 and the rear end 188 of the lower sealing member 184 toallow free movement of the valve assembly 183 without interfering withthe lever 173. The corrugations 194a and 194b in the flanges 193a and193b allow easy axial displacement of the valve assembly 183.

If the user requires to aspirate blood and anticoagulant at the maximumflowrate at the same time without using the self-regulating feature ofthe canula in accordance with the present invention he or she candepress the outside end of the lever 174. The fork 175 then pressesupwardly on the valve assembly 183 so that the upper sealing memberblocks the air vent 114 by pressing the lip seal 190 against the valveseat 181 and the lower sealing member 184 is moved as far as possiblefrom its rest position to allow the anticoagulant to flow at the maximumflowrate. As shown in FIG. 10, the outside end 174 of the lever 173 isadvantageously on the lefthand side of the canula so that the user caneasily operate the lever 173 with his or her thumb while holding thecanula in his or her right hand.

The device in accordance with the invention has been tested by theinventor, without retransfusion, on a sample of 15 persons, five malesand ten females. The average age of the subjects was 57 (age range from18 to 86 years).

Table 1 below lists the surgical procedures carried out on the patients.

                  TABLE 1                                                         ______________________________________                                        long saphenous vein removal                                                                        2                                                        femoropopliteal bypass                                                                             2                                                        aorto-bifemoral bypass                                                                             2                                                        restoration of vascular flow                                                                       4                                                        endoluminal angioplasty                                                                            2                                                        splenectomy          1                                                        cholecystectomy      1                                                        bypass               1                                                        ______________________________________                                    

The average quantity of blood recovered was 540 cm³ (range from 100 to650 cm³).

The plasma haemoglobin level was measured in samples of blood recoveredfrom each patient by the device in accordance with the invention(referred to hereinafter as "autotransfused blood"). Table 2 belowsummarizes the results.

                  TABLE 2                                                         ______________________________________                                        Patient    Plasma haemoglobin (g/dl)                                          ______________________________________                                        1          0.5                                                                2          0.3                                                                3          0.4                                                                4          0.6                                                                5          0.4                                                                6          0.3                                                                7          0.3                                                                8          0.6                                                                9          0.6                                                                10         0                                                                  11         coagulation                                                        12         0.1                                                                13         0.3                                                                14         0.2                                                                15         0.4                                                                Average    0.3                                                                ______________________________________                                    

Fibrin deterioration products (FDP) were measured for 14 autotransfusedblood samples from 14 patients (patients 1 to 10 and 12 to 15).

Table 3 below gives the number of samples corresponding to variousranges of FDP values.

                  TABLE 3                                                         ______________________________________                                        FDP (μg/l) Number of samples                                               ______________________________________                                        <10           2                                                               1-20          1                                                               20-40         1                                                               40-80         2                                                                80-160       1                                                               160-320       2                                                               320-640       3                                                                 640-2 560   2                                                               Total         14                                                              ______________________________________                                    

Table 4 below gives the breakdown of 15 autotransfused blood samplesfrom 15 patients as a function of the measured level of heparin in thesamples.

                  TABLE 4                                                         ______________________________________                                        Heparin (U/ml) Number of samples                                              ______________________________________                                        <0.05          4                                                              0.09           1                                                              0.28           1                                                              0.40           1                                                              0.41           1                                                              0.7            1                                                              >0.7, <0.8     3                                                              >0.8           1                                                              coagulation    1                                                              0.1 (uncontrolled                                                                            1                                                              coagulation)                                                                  Total          15                                                             ______________________________________                                    

Table 5 below gives the breakdown of 15 autotransfused blood samplesfrom 15 patients as a function of the measured prothrombin level (PL) ofthese samples.

                  TABLE 5                                                         ______________________________________                                        PL (%)       Number of samples                                                ______________________________________                                        <10          9                                                                13           1                                                                26           1                                                                42           1                                                                44           1                                                                59           1                                                                coagulation  1                                                                Total        15                                                               ______________________________________                                    

Table 6 below compares various measurements on 15 blood samples from the15 patients with 15 autotransfused blood samples from the same patients.

                  TABLE 6                                                         ______________________________________                                                               Autotransfused                                                     Patients   blood samples                                          Parameter                                                                             Units     Mean    Max-Min                                                                              Mean  Max-Min                                ______________________________________                                        Erythro-                                                                              × 10.sup.6 /mm.sup.3                                                              4.27    3.44-5.25                                                                            2.45  0.47-4.46                              cytes                                                                         Leucocytes                                                                            × 10.sup.3 /mm.sup.3                                                              9.05    5.4-23 5.67  1.9-12.7                               Hematocrit                                                                            %         39.6    39.9-48                                                                              23.5  4.1-41.9                               Haemo-  g/dl      13.31   11.5-15.8                                                                            7.72  1.6-13.5                               globin                                                                        Platelets                                                                             × 10.sup.3 /mm.sup.3                                                              294.9   154-513                                                                              89.4  20-196                                 ______________________________________                                    

There was little deterioration of the blood collected, which wasrelatively rich in platelets. Coagulation was not compromised andretransfusion could have been carried out without difficulty.

I claim:
 1. Suction device for autotransfusion during surgery comprisinga suction canula (1; 101) having a tubular suction nozzle (5; 105)communicating with an interior passage (6, 9; 106, 109) of said canula(1;101), said passage (6, 9; 106, 109) of the canula being connected toa blood collection storage vessel (41) adapted to be depressurized by avacuum source (40), said passage (6, 9; 106, 109) of the canulacommunicating with an anticoagulant feed circuit (42, 47, 12, 12a, 15,7; 112, 112a) incorporating an anticoagulant feed control valve (15;115), characterized in that:--said control device includes anindependent vacuum circuit (13, 44, 45, 50, 43; 113, 113a) adapted toaspirate only air and connected to the vacuum source (40), to the bloodcollection storage vessel (41) and to the control valve (15; 115) --thecontrol valve (15; 115) includes a vacuum chamber (49; 149) connected tosaid vacuum circuit (13, 44, 45, 50, 43; 113, 113a), said vacuum chamber(49; 149) having a deformable wall (29; 193b) connected to a closuremember (30; 184) of the anticoagulant circuit adapted to shut off theanticoagulant feed circuit (42, 47, 12, 12a, 15, 7; 112, 112a) and saidclosure member (30; 184) being urged towards a closed position byelastic means (28; 128) and adapted to be urged towards an open positionby deformation of said deformable wall (29; 193b) when there is asufficient pressure drop in the vacuum chamber (49; 149), and --thevacuum circuit (23, 13, 44, 45, 50, 43; 113, 113a) communicates with anair vent (14; 114) adapted to be shut off manually.
 2. Suction canulafor autotransfusion during surgery comprising a canula body (2; 102,151) forming a sleeve and having a tubular suction nozzle (5; 105)communicating with an interior passage (6, 9; 106, 109) of said canula(1; 101), said passage (6, 9; 106, 109) of the canula being connected toa blood collection storage vessel (41) adapted to be depressurised by avacuum source (40), said passage (6, 9; 106, 109) of the canulacommunicating with an anticoagulant feed passage (12, 12a; 112, 112a)incorporating an anticoagulant feed control valve (15; 115),characterized in that:--said canula includes an independent vacuumpassage (13; 113, 113a) adapted to aspirate only air connectable to thevacuum source (40) and connected to the control valve (15; 115), --thecontrol valve (15; 115) includes a vacuum chamber (49; 149) connected tosaid vacuum passage (13; 113, 113a), said vacuum chamber (49; 149)having a deformable wall (29; 193b) connected to a closure member (30;184) of the anticoagulant passage adapted to shut off the anticoagulantfeed passage (12, 12a; 112, 112a) and said closure member (30; 184)being urged towards a closed position by elastic means (28; 128) andadapted to be urged towards an open position by deformation of saiddeformable wall (29; 193b) when there is a sufficient pressure drop inthe vacuum chamber (49; 149), and --the vacuum passage (13; 113, 113a)communicates with an air vent (14; 114) adapted to be shut off manually.3. Canula according to claim 2 wherein at least part of the canula istransparent so that a user can see the blood flowing in said canula. 4.Canula according to claim 2 wherein the closure member of theanticoagulant passage (30; 184) is movable between its closed positionand a maximally open position to define a cross-section of theanticoagulant passage which varies continuously between zero and amaximal value.
 5. Canula according to claim 2 wherein said elastic means(28) of the control valve (15) comprises a compression spring (28) inthe vacuum chamber (49) and the valve (15) includes means (26) foradjusting the compression force of the spring (28).
 6. Canula accordingto claim 2 wherein said deformable wall (29) of the vacuum chamber has afirst side communicating with the vacuum chamber and a second sidecommunicating with the anticoagulant feed circuit.
 7. Canula accordingto claim 2 wherein:--the closure member (184) of the anticoagulantpassage is fastened to a closure member (185) of the vent (114), --bothclosure members are movable between a rest position in which theanticoagulant passage closure member (184) shuts off said anticoagulantpassage and the air vent closure member (185) opens the air vent and aforced active position in which the anticoagulant feed passage closuremember (184) opens said anticoagulant feed passage to the maximum andthe air vent closure member (185) shuts off the air vent, --both closuremembers are mechanically coupled to actuator means (173) for moving thetwo closure members between their rest and forced active positions. 8.Canula according to claim 7 wherein said deformable wall (193b) of thevacuum chamber has a first side communicating with the vacuum chamberand a second side open to the atmosphere and the canula furthercomprises a deformable wall (193a) of the anticoagulant circuit having afirst side communicating with the anticoagulant circuit and a secondside open to the atmosphere, said deformable wall (193a) of theanticoagulant circuit being also fastened to the two closure members(184, 185), and said actuator means comprise a lever (173) connected tothe two closure members by first articulation means (175) disposedbetween the two deformable walls and said lever (173) is connected tothe body of the canula by second articulation means (176), said lever(173) also having one end (174) projecting from the body of the canula.9. Canula according to claim 8 wherein the two closure members (184,185) are connected by a rod (186) having a cross-section smaller thanthat of the closure members and said first articulation means of thelever (173) comprise a fork (175) engaged with said rod (186). 10.Canula according to claim 8 wherein:--the body of the canula includes asleeve (102) having a front end (103) and valve means (151) fixed to thefront end of the sleeve, said valve means including a base body (156),an intermediate ring (157) and a valve body (158) in a stackedarrangement, --the two closure members (184, 185) and the rod (186)connecting them move axially in a cylindrical recess (168) extendingthrough the intermediate ring (157), --the intermediate ring (157)includes a lateral window (172) through which the cylindrical recess(168) of said intermediate ring is open to the atmosphere, --the lever(173) is moulded in one piece with said intermediate ring (157), saidlever passes through said lateral window (172) and said secondarticulation means comprise two bridges of material (176) between thelever and the intermediate ring.
 11. Canula according to claim 10wherein the anticoagulant feed passage closure member (184) is made froman elastomer material, the deformable wall (193a) of the anticoagulantcircuit is a flexible wall in one piece with the anticoagulant feedpassage closure member (184), the air vent closure member (185) is madefrom an elastomer material, the deformable wall (193a) of the vacuumchamber is a flexible wall in one piece with the air vent closure member(185), the deformable wall (193a) of the anticoagulant circuit has anouter peripheral edge (195a) trapped between the base body (156) and theintermediate ring (157) and the deformable wall (193b) of the vacuumchamber has an outer peripheral edge trapped between the valve body(158) and the intermediate ring (157).
 12. Canula according to claim 6wherein the anticoagulant feed passage closure member (184) is made froman elastomer material and the deformable wall (193b) of the vacuumchamber is a flexible wall in one piece with the anticoagulant feedpassage closure member (184).